Many of today's most popular electronic devices are shrinking in size while multiplying in features and function. Devices like hand held computers, personal audio/video players, cell phones with video recorders built in or personal global positioning systems are stressing the packaging capabilities as we know them today. Devices that need shorter signal paths cannot afford to have signals routed out of a package, through a printed circuit board, and back into another package. In order to enable shorter paths, some manufacturers of integrated circuit wafers have developed a through-hole via technology in the semiconductor wafer. While creating a much shorter interconnect path, this technology has created a difficult packaging problem that may adversely affect the reliability of the end products as well as reducing the manufacturing yields.
The conventional wafer scale packaging techniques utilize flip chip integrated circuit wafers mounted on a re-distribution substrate or thin film structure that provides a means for attaching the integrated circuit to the next system level. When integrating the latest wafer technology, having through-hole vias, other possibilities exist to allow flexible packaging. One possibility is to mount the wafer on the substrate with the backside of the wafer toward the substrate. In this configuration the active side contacts are available to connect another integrated circuit function.
The through hole via provides very efficient distribution of power and heat. It also presents a difficult attachment issue. The reliability of the die attach may be compromised by voids that form in the die attach material within the through-hole via. Another issue that can degrade the reliability of the device is that out-gassing of the die attach material during subsequent processing of the package could fracture the narrow end of the through hole via.
If the die is not firmly attached to the substrate forming the package bottom, thermal expansion and contraction will quickly damage the device, rendering it inoperative in a short period of time.
Thus, a need still remains for semiconductor wafer scale package system that can support wafers with through-hole vias. In view of the lower source voltages and distribution and increasing levels of integration, it is increasingly critical that answers be found to these problems. In view of the ever-increasing commercial competitive pressures, along with growing consumer expectations and the diminishing opportunities for meaningful product differentiation in the marketplace, it is critical that answers be found for these problems. Additionally, the need to save costs, improve efficiencies and performance, and meet competitive pressures, adds an even greater urgency to the critical necessity for finding answers to these problems.
Solutions to these problems have long been sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.